Driving and stopping mechanisms for sewing machines



g- 23, 1966 R. e. AKERLEY ETAL 3,267,895

DRIVING AND STOPPING MECHANISMS FOR SEWING MACHINES Filed 1963 5 Sheets-Sheet l f 1 I l 3 J U m 0 a e w e e Q Q V I n w o g 3- o o e r 0 2 0 9 Q 0 O S Q N N [nvenzors N Pabcf'tG. Alcr'ley Jase sh R [oannz'ZZi R 3 By zheir Attorney g- 23, 1966 R. G. AKERLEY ETAL 3,267,895

DRIVING AND STOPPING MECHANISMS FOR SEWING MACHINES Filed Feb. 27. 1963 5 Sheets-Sheet 2 g- 23, 1966 R. G. AKERLEY ETAL 3,267,895

DRIVING AND STOPPING MECHANISMS FOR SEWING MACHINES Filed Feb. 27, 1963 5 Sheets-Sheet 'J Aug. 23, 1966 R. G. AKERLEY ETAL 3,267,895

DRIVING AND STOPPING MECHANISMS FOR SEWING MACHINES Filed Feb. 27. 1963 5 Sheets-Sheet 4 g- 23, 1966 R. G. AKERLEY ETAL 3,267,895

DRIVING AND STOPPING MECHANISMS FOR SEWING MACHINES Filed Feb. 2'7 1963 I 5 Sheets-Sheet 5 United States Patent 3,267,895 DRIVING AND STOPPING MECHANISMS FOR SEWING MACHINES Robert G. Akerley and Joseph R. Ioannilli, Beverly, 'Mass.,

assignors to United Shoe Machinery Corporation,

Boston, Mass., a corporation of New Jersey Filed Feb. 27, 1963, Ser. No. 261,342 11 Claims. (Cl. 112219) This invention relates to improvements in driving and stopping mechanisms of the type disclosed in United States Letters Patent No. 1,233,539, granted July 17, 1917, upon application of Fred Ashworth and, more particularly, of the type ordinarily employed in a lock stitch shoe outsole sewing machine similar to that disclosed in an application for United States Letters Patent, Serial No. 208,847, filed July 10, 1962, now Patent No. 3,112,278, in the names of the present inventors et al.

In the driving and stopping mechanism of the application noted, easy and accurate control without frequent adjustment is rendered possible in a heavily constructed stitching machine of the type referred to, for bringing it to rest at a predetermined stop position by the use of a hydraulic displacement unit mechanically connected to a main sewing shaft in the machine and a flow restricting circuit selectively connecta'ble to the outlet conduit of the hydraulic displacement unit, the flow restricting circuit acting to bring the sewing shaft to rest within a single rotation of the sewing shaft. For this purpose the hydraulic displacement unit of the application consists of a motor of the sliding vane type driven from a pair of pumps, one of large capacity and the other of small capacity acting though a treadle controlled variable pressure compensated valve. While the driving and stopping mechanism of the application is extremely versatile and easily controlled it requires the use of complex and bulky equipment for the machine of the Ashworth patent and cannot be applied to it without complicated and extensive changes in the construction of the machine.

It is an object of the present invention to provide a driving and stopping mechanism for a heavily constructed shoe ontsole stitching machine, in which the accuracy of stopping obtainable with the mechanism of the prior application will be retained without the necessity for driving the machine with a hydraulic motor on the sewing shaft of the Ashworth machine or employing pumps separate from the sewing shaft to provide a supply of hydraulic pressure, as required by the construction disclosed in the application.

A further object is to provide an improved hydraulic stopping mechanism for a shoe outsole stitching machine employing a friction clutch for actuating the machine.

A still further object of the invention is to simplify and improve the construction of the driving and stopping mechanism of the prior application, by way of ease of both adjustment and general servicing.

In the nature of a hydraulic driving and stopping mechanism, it is unavoidable for heat to be developed necessitating dissipation wherever substantial amounts of power are transmitted through hydraulic fiow. Such dissipation of heat may present problems in radiation and discomfort for an operator of a machine equipped with such driving and stopping mechanism. Also hydraulic components of such driving and stopping mechanism may cause difficulty in adjustment or servicing through the need of special testing equipment, so that extensive retraining of an operator may be required. According to another object of the invention a machine provided with a friction clutch for driving it is conveniently adapted for use with a hydraulic stopping mechanism without also requiring full application of a hydraulic driving mecha- 3,257,895 Patented August 23, 1966 ice nism to the machine. In this way an operator is not burdened with the necessity for a full understanding of a more complex hydraulic system required for driving a heavily constructed shoe outsole stitching machine.

To the ends briefly outlined a main sewing shaft of a machine of the type referred to is driven by a suitable rotating means cap-able of variable. control by an operator and connected mechanically to a hydraulic displacement unit having a flow restricting circuit connectable to it for retarding rotation of the sewing shaft just before being brought to rest, a stop cam on the sewing shaft having a radial shoulder arranged to be engaged by a pivorally mounted dog movable into and out of the path of the cam by the operator, in which machine an arm is provided to be engaged by the dog when moved into the path of the cam, the arm being connected to the flow restricting circuit to render that circuit effective in retarding rotation of the sewing shaft. By such arrangement, when the shoulder engages the dog the speed of rotation of the sewing shaft will be so reduced that engagement of the shoulder with the dog will be sufficient to bring the shaft into an accurate stopping position without danger of damage to the shoulder or dog and without the necessity of complex electrical controls, as in the machine of the prior application. Preferably, the flow restricting circuit includes a throttling orifice and a by-pass valve and the arm engaged by the dog is mechanically connected to close the by-pass valve before bringing the machine to rest. Such arrangement has several advantages over the use of relatively complex electrical solenoid circuits for rendering the fiow restricting orifice operative within the required time interval, as in the machine of the prior application. If a blocking device also is provided to prevent entry of the dog into the path of the stop shoulder when the sewing shaft is a minor fraction of a full rotation ahead of stopping position, then the full benefit of the mechanical connections is obtained without recourse to the electrical solenoid controlling circuits.

In one form of the invention a friction clutch is utilized under the control of a treadle, the treadle being arranged for actuating the dog out of the path of the shoulder on the cam and a source of hydraulic pressure actuated by the sewing shaft is utilized to rotate it after the friction of the clutch is terminated until such time as the stop shoulder comes into engagement with the stop dog at the end of a seam inserted by the machine.

To provide the source of hydraulic pressure when the machine is driven by a friction clutch an accumulator is connected to the hydraulic displacement unit and the pressure in the accumulator is developed by rotation of the sewing shaft during sewing operations.

These and other features of the invention, as hereinafter described and claimed, will readily be apparent to those skilled in the art from the following detailed specification, taken in connection with the accompanying drawings, in which:

FIG. 1 is a perspective view looking from the front portions of a sewing head in a machine embodying the features of the present invention;

FIG. 2 is a detail view, looking from the left side of the machine of FIG. 1 and showing on an enlarged scale a set of treadle controlled connections actuated by the operator of the machine;

FIG. 3 is a detail side view on a further enlarged scale looking from the right of other portions of the treadle connections and showing the parts in positions assumed before the machine is finally stopped;

FIG. 4 is a detailed view in front elevation of a stopping dog latch shown in FIG. 3;

FIG. 5 is a right side detail view of the connections shown in FIG. 3 but taken with the stopping dog latch in a position assumed when the machine is at rest at the end of a seam;

FIG. 6 is a detail view in front elevation of the stopping dog latch shown in FIG. 5, illustrating the latch released from looking position; and

FIG. 7 is a schematic hydraulic system diagram of the driving and stopping mechanism employed in the machine.

The sewing machine illustrated in the drawings is a curved hook needle lock stitch machine, similar to that disclosed in United States Letters Patent No. 2,271,611 granted February 3, 1942, upon application of Fred Ashworth et al., the driving mechanism being composed of a mechanical friction clutch and the low-speed mechanical stopping mechanism being replaced by a simplified and improved hydraulic stopping mechanism for retarding the operation of the machine and bringing it to rest within a single cycle of the machine, the final stopping position being determined by a positive mechanical stop, as disclosed in the prior patent.

Referring to FIG. 1 of the drawings, the machine has a main frame 10, in which are mounted a curved hook needle 12, a work support 14, a presser foot 16, a shuttle 18, and other stitch forming and work feeding devices actuated by a main sewing shaft 20. For driving the main sewing shaft the left end has secured to it a hand wheel 22, toward and from which there is slidable and rotatable on the sewing shaft a driving pulley 24 comprising with the hand wheel 22 a main friction clutch. For increasing or decreasing the friction of the clutch and thus, the speed of rotation of the sewing shaft, a clutch collar on the pulley 24 is engaged by a curved arm on a bell crank lever 26. The bell crank lever 26 is fulcrumed at 28 on the machine frame and has a horizontal arm engaged by either of two collars 30 disposed on a treadle rod 32 above and below the arm (see also FIG. 2). When the treadle rod is depressed the upper collar 30 engages the lever 26 and the friction of the clutch 22, 24 is increased sufficiently to start rotation of the sewing shaft 20 in the direction of the arrow in FIG. 3. The lower end of the rod 32 is connected to a conveniently disposed treadle 34 (see FIG. 7) and a spring 36 causes the treadle and the rod 32 to rise when the treadle is released by an operator of the machine.

In the machine of the prior patent, when the operator releases the treadle the friction of the clutch is decreased and the main sewing shaft is brought to rest by the engagement with a stopping dog of a shoulder on the cam secured to the sewing shaft. In the present machine the sewing shaft 20 has a cam 38 (FIG. 3) provided with a stop shoulder 40 arranged to engage a stopping dog 42 to bring the machine to rest in a predetermined critical position with the needle and other stitch-forming devices disengaged from the work and other auxiliary operations completed, so that the work 'may be readily removed and a new work piece introduced. In starting the machine in operation the stopping dog 42 is moved out of the path of the cam 38 as the treadle 34 is depressed. For this purpose the upper end of the treadle rod 32 is pivotally connected to a calm lever 44 (FIGS. 2 and 7) engaging a roll 45 on an arm 46 secured to a shaft 48, also having integral with it an arm 50. The shaft 48 rotates in a fixed part of the machine and the arm 50 engages the lower end of a set screw 52 carried by a laterally projecting arm of the stopping dog 42, the stopping dog be ing pivoted on a hub of an auxiliary operation performing lever 54 (see also FIG. 3). The stopping dog is pressed resiliently into the path of the cam 38 by yielding means comprising a spring 55. When the cam lever engages the roll 45 on the arm 46 the stopping dog is moved out of the path of the cam so that the sewing shaft may rotate freely. When the treadle 34 is released to bring the machine to rest by decreasing the friction in the clutch 22, 24, the stopping dog is locked out of the path of the cam until the stop shoulder is a major fraction of a complete rotation away from the stopping dog so that ample opportunity is given for reducing the speed of the sewing shaft to a point where there is no possibility of damage to the parts when the shoulder engages the stopping dog. As more fully disclosed in the Copithorne et a1. application and best illustrated in FIGS. 3 to 6, inclusive, of the present application.

For locking the stopping dog out of the path of the cam 38 the stopping dog has rotatable on it a releasable blocking arm 56 for engagement with the auxiliary open ation performing lever 54 (FIGS. 3 and 4). The blocking arm has a finger 58 projecting into the path of the cam 38 at a position to be engaged by the shoulder on the cam While the stopping dog is out of the path of the cam. The stopping dog is retained in this position yieldingly by a spring 60 and is moved out of the path of the cam when the shoulder is a minor fraction of a full rotation in advance of the point where the shoulder is intended to engage the dog. In the positions of the parts shown in FIGS. 3 and 4, the blocking arm finger 58 is about to be engaged by the shoulder on the cam. The stopping dog is then released for movement into the path of the cam, as shown in FIGS. 5 and 6. It is this movement of the stopping dog into the path of the cam which renders operative the hydraulic stopping mechanism for retarding and bringing to rest the sewing shaft.

The hydraulic stopping mechanism of the present machine consists of a hydraulic displacement unit 61 mechanically connected to the right end of the sewing shaft 20. For retarding rotation of the sewing shaft the displacement unit 61 which is of the sliding vane type and has an outlet connection 62 provided with an adjustable flow restricting circuit comprising a variable throttling orifice 64 (FIG. 7), and a combined pressure relief and pilot controlled by-pass valve 66 connected in parallel to the throttling orifice. The exhaust end of the outlet pipe terminates in a sump 67 and the pilot control for the bypass valve comprises a two-position slide valve 68 actuated to close the by-pass valve by the dog when moved into the path of the cam, the pilot valve 68 being shown in by-pass closing position in FIGS. 5 and 7. In these figures the full retarding action of the orifice 64, accordingly, is being exerted on the hydraulic displacement unit 61 to slow the shaft down to a safe stopping speed. As soon as the treadle 34 is depressed to start the machine in a new operation, the pilot valve 68 opens the by-pass valve 66 for free flow of fluid through the displacement unit 61, so that no further retarding action occurs.

Opening the by-pass valve 66 is effected when the laterally extending arm of the dog 42 is shifted by the treadle connections to raise the laterally extending dog arm until it engages a forwardly projecting arm of a lever 70 having at its rearward end a horizontally disposed leaf spring 72 and a central fulcrum stud 73 mounted on the machine frame. The leaf spring 72 overlies and engages a roll 74 on a vertical plunger 76 connected with the slide valve 68, so that when the arm of the dog 42 is raised while the dog is moving out of the path of the cam 38, the bypass valve 66 is opened through a pilot connection 78, indicated by a broken line, and all retarding action is removed from the displacement unit 61.

To close the by-pass valve 66 the pilot valve 68 is raised yieldingly by a compression spring 80, which acts against the force of the leaf spring 72 but is unable to overcome this force until the stopping dog is moved out of the path of the cam 38. In this way the leaf spring 72 causes actuation of the pilot control valve 68 while leaving opportunity for more or less motion than is imparted to the pilot valve.

To insure that the main sewing shaft will be brought uniformly into stopping position with the shoulder 40 on the cam in positive engagement with the stopping dog 42, even though there is a possibility that the engagement of the shoulder and the dog is of suflicient impact to cause bouncing and retrograde turning of the shaft, the machine illustrating the invention is provided with a source of fluid supply under pressure for rotating the sewing shaft until the stop shoulder comes into secure engagement with the stopping dog. To this end the hydraulic system contains an accumulator 82, the pressure in which is produced by rotation of the sewing shaft 20 during sewing operations.

The sewing shaft 20 has mounted on it a rotary vanetype pump 84 connected to an outlet pipe 86 and a check valve 88 running to the accumulator. The pump 84 has an inlet pipe 90 connected to a strainer 92 immersed in the sump 67. The accumulator is connected to the displacement unit 61 by a tube 94 and the pump and the displacement unit are arranged on the shaft in such relation that the fluid displaced by the pump 84 is slightly greater than that displaced by the unit 61, both the pump and the displacement unit acting to transfer fluid in the same direction through the pipe 86 and the tube 94. If the Pump has a rating of 9 gallons per minute, the displacement unit has a rating of only 8 gallons per minute. In this way the accumulator will be charged at a rate of 1 gallon per minute.

To render the pump 84 inoperative while the accumulator is driving the hydraulic displacement unit 61, there is provided a vent in the form of a pipe 96 in the outlet tube 86 between the pump and the displacement unit. In this way the pressure stored in the accumulator is able to operate the displacement unit readily without any retarding action from the pump. When the treadle is released at the end of a sewing operation the vent pipe 96 is connected through the pilot valve 68 to the sump 67. Depressing the treadle 34 to start the machine in operation causes the pilot valve 68 to close the vent pipe 96, so that the pump 84 may charge the accumulator 82. After the accumulator has been fully charged excessive pressures are avoided by the use of a relief valve 98 connected in the outlet tube 86 for the pump.

The nature and scope of the invention having been indicated and a particular embodiment having been described, what is claimed is:

1. A sewing machine having stitch-forming devices, a main sewing shaft for actuating the stitch-forming devices, means for driving the sewing shaft under variable control by an operator of the machine, a hydraulic displacement unit, means mechanically connecting said displacement unit to the sewing shaft, a flow restricting circuit connectable to the displacement unit to retard rotation of the sewing shaft, a stop cam on the sewing shaft having a radial shoulder and a pivotally mounted dog arranged to move into and out of the path of said cam and to be engaged by the shoulder when the shaft reaches a predetermined stopping position, in combination with an arm engaged by the stopping dog when moved into the path of the cam and means mechanically connecting said arm to the flow restricting circuit to render the flow restricting circuit effective to retard rotation of the sewing shaft.

2. A sewing machine, as in claim 1, in which the flow restricting circuit includes a throttling orifice and a by-pass valve, and the arm is mechanically connected to close the by-pass valve when engaged by the stopping dog.

3. A sewing machine, as in claim 2, in which a blocking device is provided to prevent entry of the dog into the path of the stop shoulder when the sewing shaft is in a minor fraction of a full rotation ahead of stopping position.

4. A sewing machine, as in claim 1, in which the driving means for the sewing shaft includes a friction clutch, a control treadle for increasing or decreasing the friction of the clutch and for actuating the dog out of the path of a shoulder on the stop cam and yielding means for moving the dog into the path of the cam, and their also is provided a source of fluid supply under pressure for rotating the sewing shaft until the stop shoulder comes into engagement with the stopping dog when the friction of the clutch is decreased at the end of a seam.

5. A sewing machine, as in claim 4, in which the supply of fluid comprises an accumulator, the pressure in which is produced by rotation of the sewing shaft during sewing operations.

6. A sewing machine, as in claim 5, in which there is provided a bypass in the flow restricting circuit comprising a valve actuated by the dog when moved into the path of a cam to close the b-y-pass.

7. A sewing machine, as in claim 6, in which there is also provided a hydraulic pump mechanically connected to the sewing shaft for increasing the pressure in the accumulator during sewing operations.

8. A sewing machine, as in claim 7, in which the capacity of the pump is greater than the capacity of the hydraulic displacement unit, and the accumulator is connected hydraulically between the pump and the displacement unit to cause the extra capacity of the pump to supply fluid to the accumulator.

9. A sewing machine, as in claim 7, in which there also is provided a vent between the pump and the hydraulic displacement unit arranged to open the outlet of the pump when the flow restricting circuit is retarding the sewing shaft.

10. A sewing machine, as in claim 8, in which a check valve is provided between the pump and the accumulator to prevent release of pressure in the accumulator when the outlet of the pump is vented.

'11. A sewing machine, as in claim 9, in which the vent is opened by the valve actuated by the dog as the bypass is being closed.

References Cited by the Examiner UNITED STATES PATENTS 3/1964 Carter 1212-2J19 7/1964 Oopithorne 112219 

1. A SEWING MACHINE HAVING STITCH-FORMING DEVICES, A MAIN SEWING SHAFT FOR ACTUATING THE STITCH-FORMING DEVICES, MEANS FOR DRIVING THE SEWING SHAFT UNDER VARIABLE CONTROL BY AN OPERATOR OF THE MACHINE, A HYDRAULIC DISPLACEMENT UNIT, MEANS MECHANICALLY CONNECTING SAID DISPLACEMENT UNIT TO THE SEWING SHAFT, A FLOW RESTRICTING CIRCUIT CONNECTABLE TO THE DISPLACEMENT UNIT TO RETARD ROTATION OF THE SEWING SHAFT, A STOP CAM ON THE SEWING SHAFT HAVING A RADIAL SHOULDER AND A PIVOTALLY MOUNTED DOG ARRANGED TO MOVE INTO SAID OUTER OF THE PATH OF SAID CAM AND TO BE ENGAGED BY THE SHOULDER WHEN THE SHAFT REACHES A PREDETERMINED STOPPING POSITION, IN COMBINATION WITH AN ARM ENGAGED BY THE STOPPING DOG WHEN MOVED 